Process for the desalting of salt solutions by electrodialysis

摘要

Diaphragms consisting wholly or in part of ion-exchange material are made by the following methods: (1) 1 mol. of phenol is heated with 1.2 mols. of concentrated sulphuric acid at 100 DEG C. for two hours.; 5 c.c. of this reaction mixture are mixed with 5 c.c. of a 30 per cent formalin solution and heated to 70 DEG C. so that a clear cherry-red solution is obtained. The solution is poured into glass dishes which are covered and heated in a drying chamber at 90 DEG C. until gel formation and solidification takes place. The membranes produced may be afterwards sulphonated; (2) freshly distilled styrene is mixed in one case with 6 per cent and in other cases with 9 per cent and 12 per cent by weight respectively of divinyl benzene and polymerized after addition of 0.2 per cent by weight of benzoyl peroxide in a vessel placed in boiling water. The polymerisate sets as a rod which is cut into discs which are afterwards sulphonated; (3) 4.3 gms. of anhydrous polyethyleneimine is dissolved in 10 c.c. of methanol and the solution is mixed with varying quantities of epichlorhydrin. The mixtures are poured into glass dishes and condensed in a drying chamber. Specification 694,223, [Group XXXVI], is referred to.